Diaphragm for cameras



(No Model.) 4 Sheets-Sheet 1.

M. LEVY. DIAPHRAGM FOR CAMERAS.

No. 532,326. Patented Jan. 8, 1895.

WIIJVE'SSES iTdW m: mums FEYERS cov PHOTO-UTHD. WASHINGTON. n c.

(No Model.) 4 SheetsSheet 2.

M. LEVY.

DIAPHRAGM FOR CAMERAS. 53 ,326. Patented Jan. 8, 1895.

WZZWESSE'S (No Model.) T 4 Sheets-Sheet 3 M. LEV Y.

DIAPHRAGM FOR CAMERAS. No. 532,326. Patented Jan. 8, 1895.

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(No Model) 4 Sheets-Sheet 4.

M. LEVY DIAPHRAGM FOB CAMERAS.

No. 532,326. Paien'ted Jan. 8, 1895.

WJIWESSES I j/v'mwz 071? UNITED STATES PATENT OFFICE.

MAX LEVY, OF PHILADELPHIA, PENNSYLVANIA.

DIAPHRAGM FOR CAMERAS.

SPECIFICATION forming part of Letters Patent N 0. 532,326, dated January8, 1895.

Application filed August 81, 1893.

To all whom it 71mg concern;

Be it known that I, MAX LEVY, a citizen of the United States of America,residing at Philadelphia, in the county of Philadelphia and State ofPennsylvania, have invented certain new and useful Improvements inDiaphragms for Cameras; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to lettersof reference marked thereon, which form a part of this specification.

The invention relates to improvements in diaphragms for photographiclenses,the same being especially designed for use in the production ofhalf-tonephoto-m echanical engravings, the improvement relatingparticularly to the means of producing negatives through cross-linedscreens.

The invention is based upon the fact that in making the so-calledhalf-tone negative through a cross-lined screen the effect is to produceupon the sensitive plate through each aperture of the screen a perfectreproduction of the opening in the lens through which the light isadmitted. Following out this discovery and drawing the equivalent of theopaque cross-lines of a screen upon paper, and further drawing upon thediagram a series of squares representing the lens-aperture with theirsides at an angle of forty-five degrees with said cross-lines (seeDiagram 1), Figure 1),it will at once be seen that there are formedopaque squares where the lines overlie or cross, and these opaquesquares are brought out more prominently than would be the case with around lens-aperture or with a square aperture the sides of which arearranged in the same position relative to the lines of the screen.Furthermore, there are many instances in which a diaphragm with a squareaperture will not sufficiently accomplish the result desired, and thisis notably the case where the subject to be reproduced has relativelydark high lights and light shadows, or, as commonly expressed, thesubject is flat or wants contrast or brilliancy.

In such a case I extend either two or four of the corners of the squareaperture, these extensions being of relatively small size as com- SerialNo. 484,458. (No model.)

pared to the main aperture, and the light transmitted through them in anordinary exposnre is only sufficient to produce in the highest lights ofthe subject an action which will respond to the subsequent processes ofintensification. In elfect the result is somewhat analogous to the caseof a round aperture where a small stop is used for the general subjectand a larger one for the high lights, both openings operating at thesame time; but, as will be seen by reference to a diagram as aboveindicated, the light admitted by the excess of aperture in the foregoinganalogy will fall only between the intersections of the opaque lines ofthe screen, thus greatly exaggerating the tendency to form the desireddots and without undue loss in the sharpness of the lines.

In still further applying my invention, if an aperture of proper size asrelated to the distance between the screen and sensitive plate andhaving the central light blocked out be used for a portion only of theentire exposure the light admitted through the multiple aperture can bemade to fall on the sensitive plate only on those portions between theintersections of the black cross-lines and the highest lights may be inthis way almost entirely acted upon without apparent detriment to otherportions of the picture.

In practice in dealing with subjects of greatly varied character it isoften found desirable to change the character of the aperture during theprogress of a single exposure.

This invention may be applied more or less successfully in a variety ofways all of which are essentially dependent on the same factors. First,there may be at hand simply an assortment of removable diaphragms, asshown in Fig. 2, which have formed therein differentsized apertures,some square and some with extended corners, and these may be usedseparately for an entire exposure or changed during the progress of theexposure; second, a revolving disk fitted to the lens-tube as commonlyin the case of revolving diaphragms may be provided with a series ofapertures of different sizes or forms as before mentioned, and thismethod may be still further amplified and improved by having two or moreindependent disks of this character, so that one set of apertures may beused to modify the other (see Figs. 3, 1L and 5), and third, there maybe used a combination of mechanically variable "apertures that will givea choice of any desired opening from a square of any size with noprojecting corners to a similar square with large projecting eorners,and also to a square of any size with the central light blocked out, sothat any aperture may be used throughout a complete exposure or may bevaried at will during the progress of the exposure. (See Figs. 6, 7 andS).

In the accompanyingdrawings, Fig. 1 is a diagram of the lines and spacesor apertures ofa cross-lined screen, and upon this diagram areillustrated aseries of shadows which represent the action of the lightwhich passes through the openings in the screen when admitted throughthe different apertures in the diaphragm. In this figure a designatesthe effectof a round aperture as usually employed; 1), the effect whereasquare aperture is used and positioned as stated above; c, the effect ofa square aperture with two extended corners, and cl that of a squarewith four extended corners placed as I prefer to place them. Fig. 2represents the ordinary removable diaphragms with the various shapedapertures which I employ. Fig. 3 is a view of a removable diaphragmwhich is provided with a series of square apertures so arranged that aseach aperture consecutively comes into the central position of the lensits sides occupy the same position relative to the camera. Fig. 4 is aview showing a similar diaphragm, the square apertures 0 being extendedat their corners 0 Fig. 5 is a view showing a revolving diaphragm with alarge rectangular aperture and a series of apertures, each of the latterconsisting of a series of small apertures surrounding a central opaqueportion. Figs. 6, 7 and 8 are views showing modifications, thediaphragms in this case being provided with variable apertures. Fig. 0is a side elevation, partly in section, of a lenstube showing theapplication thereto of the diaphragms illustrated in Figs. 6, 7 and 8,with handles for manipulating them.

In practice I sometimes utilize the three forms of diaphragms B, G and Das shown in Fig. 2 in a single exposure. The same results are attainedby using the forms of diaphragms shown in Figs. 3, 4: and 5 which arepivoted within the 1ens-tube, in front or behind the lens or combinationof lenses; but where a combination is used it is preferred to place thediaphragms at or near the center between the lenses of the combination.These diaphragms are arranged so that the apertures can be brought on aline with each other and with the axis of the lens, and they are placedas close together as possible. The same results may be obtained by usingdiaphragms as shown in Figs. 6, 7 and 8, in which instead of revolvingdiaphragms I use diaphragms which are mounted in the lens-tube centrallyon a line with the axis of the lens; and the diaphragm shown in Fig. 6is provided with slides 7L h which when moved will give apertures ofdifferent sizes having extensions 0 which increase and decrease in widthwith the size of the aperture.

The slides are mounted on fixed pins a which pass through slots 7ttherein, and each slide is provided with a stud 7L3 engaging curvedslots in a disk h". The slides are superimposed and manipulated by thedisk 7b" which has a projecting handle h for that purpose.

In Fig. 7 a rectangular aperture is produced by the movement of the twoslidesf andf on the fixed pins a which pass through slots f therein, theslides having studs f which are engaged by curved slots in a diskf; andin Fig.8 an aperture having the central light blocked out is produced bymeans of the mov able arms g g which are mounted on the fixed pins a andare connected at theiroutor ends to a ring 9 The three different formsof diaphragms shown in Figs. 6, 7 and 8 are segarately manipulated bythe projecting handlesf g and h. The handlef operating the twoslidesfand f which form the square aperture has a pointer f and on thelens-tube are graduations f, these indicating the size of the aperturein terms of the focal-length of the lens; and attached to the handle itis a dish by means of which are manipulated the slides 7L h forming theapertures with extended corners. "When the two handles f and h are on aline with each other, or parallel, the projecting corners of the oneaperture are constantly covered by the diaphragm having the squareaperture, but as these handles are separated the pointers on the handlesand the graduations on the lens-tube indicate the exact length of theprojecting corners which are left exposed by the larger size of thesquare aperture of the diaphragm, Fig. 7. A. third scale, 9 serves toindicate the extent to which the central light is blocked outby thelapping of the four movable arms g g. A lens provided with diaphragms ofthis character when properly employed in a camera in connection with acrossline screen will yield negatives far superior to those made by themeans ordinarily employed.

In making a so-called half-tone print the usual cross-line screen isemployed in connection with the diaphragms hereinbefore described, andin reproducing a subject where the lights and shadows are pronounced theexposure would be through one of the square apertures alone, saidaperture being arranged relative to the screen so that the-dots areformed at the intersections of the cross-lines and the light projectedbehind the opaque lines of the screen between the intersections; butwhere the subject has relatively dark high lights and light shadows theexposure would be through all of the diaphragms consecutively, thesquare aperture being first used to give the central light, then thesquare aperture extended at its corners used so that IIO said extensionswill assist in throwing the light beyond or behind the opaque lines ofthe screen between their intersections, and then the diaphragm with thecentral light blocked out is used to further intensify the light behindthe opaque lines.

It is found that the exposure given by all the diaphragms consecutivelyintensifies the light on the parts of the negative behind the opaquelines between their intersections, which would not be accomplished bythe ordinary regular aperture, and the result would be practically thesame as if the subject had high lights and dark shadows.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. Adiaphragm for photographiclens-tubes provided with a rectangularaperture having extensions at the corners thereof, for use with agrating or screen for the purpose set forth.

2. In a photographic lens-tube, the combination, of a diaphragm having aseries of rectangular apertures so arranged that as each of theapertures is consecutively moved to a central position on a line withthe axis of the lens the sides of said apertures will occupy the sameposition relative to the axis of the lens, for use with a grating orscreen for the purpose set forth.

3. In a photographic lens-tube, a diaphragm having a plurality ofapertures surrounding a central opaque portion which is adapted to bepositioned in line with the axis of the lens, for use with a grating orscreen for the purpose set forth.

4. A lens-tube for the purpose set forth having a diaphragm with asquare aperture the corners of which are extended as shown, and a seconddiaphragm with a plurality of apertures surrounding a solid portion thecenter of which is adapted to be positioned in line with the axis of thelens, substantially as shown, for use with a grating or screen for thepurpose set forth.

5. In a photographic lens-tube, the combination, of a plurality ofdiaphragms, two of said diaphragms having apertures of a differentcharacter and a third diaphragm having a plurality of aperturessurrounding an opaque central portion which is adapted to be broughtinto line with the axis of the lens, for use with a grating or screenfor the purpose set forth.

6. In a photographic lens-tube, the combination, of a diaphragm having aplurality of rectangular apertures of difierent sizes with extendedcorners and a diaphragm having a plurality of square apertures ofdifferent sizes, the diaphragms being adapted to be moved to bring theapertures therein in line with each other and on a line with the axis ofthe lens, for use with a grating or screen for the purpose set forth.

7. In a photographic lens-tube, the combination, of a plurality ofdiaphragms each having a number of different-sized apertures, theapertures in the diaphragms being of different configuration, for usewith a grating or screen and for the purpose set forth.

8. In combination with a photographic lenstube, of a plurality ofdiaphragms each having an aperture of a configuration different from theapertures of the other diaphragms, the aperture in one of the diaphragmsbeing rectangular and having extensions at the corners thereof and oneof the other diaphragms having a plurality of apertures surrounding acentral opaque portion which is adapted to be positioned in line withthe axis of the lens, for use with a grating or screen for the purposeset forth.

9. In the art of making half-tone negatives the employment andcombination of the following instrumentalities: a grating or screenwhich is positioned in front of the sensitive plate in the rear of thelens-tube, a plurality of diaphragms carried by the lens-tube, saiddiaphragms having apertures the sides of which are parallel with eachother with relation to the axis of the lens and positionedin thelenstube so that the sides of said apertures will be at an angle withthe lines of the grating or screen, for the purpose set forth.

10. In a photographic lens-tube, the combination, of four slid es havingsimilar shaped apertures with extended corners and slots through whichpass fixed pins, studs project ing from the slides, together with a diskhaving curved slots with which the studs engage, and means for movingthe disk to increase or diminish the size of the aperture formed by theslides.

11. A diaphragm for photographic lenstubes made up of a plurality ofsuperimposed slides each having a rectangular aperture with an extendedcorner to present an aperture with extensions at all of the cornersthereof, substantially as shown.

12. In a photographic lens-tube, a plurality of similarly shaped slideswith apertures having extended corners and means for moving said slidesin unison, of a pair of slides having rectangularapertures and means formoving them one upon the other, the adjusting means being so constructedthat the size of the aperture formed by the diaphragm may be changedwithout changing the configuration thereof, and that the configurationof the aperture may be changed without varying the size of the apertureexcept at the corners thereof.

In testimony whereof I affix my signature in presence of two witnesses.

MAX LEVY.

Witnesses:

ADOLF HAUSSER, JEFFREY ZANKSTON.

IIC

